Hi Stefan,
I find it difficult to wipe the board when components have been
installed. Whatever I use snags on the leads; which are very sharp
by that time because they've been clipped.
I use an acid brush with bristles cut down to 3/16" or so, rub until
the flux has disolved and let the cleaner dry (after I've let as
much as possible run down the board which I hold at an angle).
With drug store IPA, a lot of residue is left. Granted, if I wipe,
I get better results. But because of the leads, I can't wipe very
well. Anything I use snags on the leads.
With 98+% IPA, more of the residue disappears. I don't know if more
of it's running off the board or going into the air. From
observation (i.e. when I use the good IPA and don't have enough
fluid to run off the edge of the board), I still get good cleaning.
This isn't the case with rubbing alcohol. I've read in many places
that this is due to the water. BTW, IPA is hygroscopic, so it
absorbs water from the air.
When I use compressed air to blow off the board after scrubbing, I
get even better results. It might make rubbing alcohol work better,
but I haven't tried.
BTW, this is the way we cleaned boards when I was a technician
repairing computers the size of refrigerators. Back then, we used
TCE (now banned) and we used compressed air to blow cleaner off the
board. That's what prompted me to start using compressed air now...
I don't know how to explain it any better. Maybe you should try the
good stuff. I've tried both and now all I use rubbing alcohol for
is to remove sticker residue from EPROMs.
Regards,
Dennis
--- In
Homebrew_PCBs@yahoogroups.com, "Stefan Trethan"
<stefan_trethan@...> wrote:
>
> On Thu, 09 Feb 2006 22:09:31 +0100, dl5012 <dl5012@...> wrote:
>
> > Hi Stefan,
> >
> >
> > The water in rubbing alcohol slows down the rate of evaporation.
> >
> > That leaves residue from some of the stuff that was disolved in
the
> >
> > alcohol or water on the board.
> >
> >
> > I know. I've tried using rubbing alcohol as a flux remover. It
> >
> > made a big mess. 98+% anhydrous isopropyl alcohol leaves a lot
> >
> > less. I found it works best when I use compressed air to blow it
> >
> > off the board instead of letting it evaporate. This might make
> >
> > rubbing alcohol work better, but I know the anhydrous stuff is
> >
> > better...
> >
> >
> > Regards,
> >
> > Dennis
>
>
> You'll have to explain that some more.
>
> As i see it, in both cases the gunk is solved into the liquid, and
a large
> percentage of the liquid with gunk is wiped off. What remains is
some
> alcohol, some gunk, and more or less water, but the amount of gunk
should
> be the same in both cases. The alcohol and water evaporartes, the
gunk is
> left behind, now severely reduced in amount.
>
> None of the gunk is removed through evaporation i'd say.
>
> So i don't see how it works like you say.
>
> I do believe there is some difference, i just don't understand how
it
> works.
>
> Besides, i use "cheap" IPA or denatured alcohol, also the cheap
variety,
> for board cleaning with no problems, but that's besides the point
i really
> want to know why you got better results with the clean stuff.
>
> ST
>